Shocking carp out of Midwest rivers not viable option

Wednesday, January 23, 2013 11:54 AM

Reuben Goforth found that the voltage necessary to kill Asian carp embryos and control the invasive species with electricity would be too high to be safe in rivers. Scientists had hoped to modify or expand low-voltage electrical barriers such as those used around Chicago waterways to direct fish from particular areas.

WEST LAFAYETTE, Ind. — One of the more promising ideas for
controlling or eliminating troublesome Asian carp populations in the Midwest’s
rivers is impractical and unsafe, according to a Purdue University
researcher.

Scientists had hoped to modify or expand low-voltage
electrical barriers such as those used around Chicago waterways to direct fish
from particular areas.

Reuben Goforth, an assistant professor of aquatic community
ecology in the Department of Forestry and Natural Resources, said the level of
electricity needed to kill Asian carp eggs in the rivers where the invasive
species has spread would be far too high.

“We were really hoping this would be a viable way to control
these Asian carp,” said Goforth, whose findings were published in the early
online version of Transactions of the American Fisheries Society. “We really
need to look at other methods.”

The several species known as Asian carp — silver carp, black
carp and bighead carp — are not native to U.S. waterways, but have been found in
rivers throughout the Midwest. These fish are competing with native species for
food and altering ecosystems.

They also are dangerous to boaters and other river users
since Asian carp can weight up to 60 pounds and are known to jump out of the
water during even minor disturbances.

“They’re softer, but imagine going 35 mph in a boat and
having something with the mass of a bowling ball hitting you in the face,”
Goforth said.

“There are cases of broken cheeks, broken noses, people
being knocked out.”

Goforth tested electrical fields on three model species —
zebrafish, goldfish and fathead minnows — which are in the same family as Asian
carp and have embryos that are similar in size.

He found that it took at least 16 volts per centimeter of
electricity to kill the embryos.

That’s in contrast with 1 volt per centimeter used in
electrical barriers around Chicago, which Goforth said have had at least one
case in which a boat too close to shore caused a substantial electrical
arc.

“Using 16 volts is just too much,” he said. “It would be
dangerous for people and other aquatic life to put that much electricity in the
water. It’s a significant hazard.

“Even if we were able to control the population with 8 volts
per centimeter, that’s a lot of electricity.”

Goforth said he would look at other methods to control Asian
carp, including using weak electrical fields or hydroacoustics to deter the fish
from optimal spawning grounds.